Cuba’s sweltering, mosquito-plagued summers have not been kind to its 11m inhabitants since the Soviet Union’s demise. For 15 years, daily power outages left homes in the dark and without fans to battle the heat and insects, while vacationing youths made do for hours without television or music and water pumps went idle.

But in the most significant sign yet that the post-Soviet crisis may finally be coming to an end, the lights have remained on this summer because of what President Fidel Castro calls his “energy revolution”.